Shipping of goods, both regionally and internationally, is conducted by several means, including rail, ship and, very often, truck. While container trucks or truck-trailer combinations are used, particularly in conjunction with rail or ship container shipping, in many places and situations, a standard flatbed truck is used. In order to protect the shipped goods from exposure to the elements, they are typically covered with tarps. In order to ensure optimal shipping conditions, a system of securing the tarps to the flatbed is required. Generally, a series of frames (known as “bows”) are attached to the flatbed and then one or more tarps are attached to the bows to create an enclosed, roughly cuboid cargo area. The most common currently known means of securing the tarps to the bows involves flaps on the tarp which overlap the bow, generally using Velcro™ or similar means. The tarp is required to be modified to include the flaps, and after repeated use the flaps do not secure as well, suggesting a need for an improved method of securing the tarps.
U.S. Pat. No. 4,902,064 issued to Tuerk et al. discloses a Conestoga-style tarp system using bows which are attached to guide rails attached to the sides of the vehicle flatbed. The rearmost bow is designed to be tilted or leaned to provide tension to the tarp and to secure the bow. The tarp is a single tarp which is extended over the bows and supported by the tension created by the positioning of the rearmost bow. The Tuerk tarp system does not disclose any use of multiple tarps, nor any means of securing the tarp to the individual bows.
U.S. Pat. No. 5,538,313 issued to Henning discloses a tarp system for a flatbed trailer including three sets of bow members (front, intermediate, rear) for supporting the tarp. The bow members are slidably mounted to guide rails running along the sides of the flatbed, thus enabling the bow members to be moved to different locations on the flatbed and for the entire assembly to be compressed or expanded as required to load and unload the vehicle. Helming is a modified version of the Tuerk system and is similarly design around a single tarp supported by tension created by bow positioning. There is no disclosure of any system using multiple tarps or any means of securing the tarps to individual bows.
U.S. Pat. No. 5,080,423 issued to Merlot et al. discloses a segmented tarp cover system. The Merlot tarp is designed as a series of segmented tarp pieces which are extended to cover the top of a cargo container, such as a rail car of truck trailer. The Merlot system is designed solely for a top covering and does not disclose any means or method of covering the sides and ends of a cargo container or surface.
All the disclosed systems require the addition of guide rails or an equivalent element to the flatbed to support the bows. Not all flatbeds are capable of having guide rails secured to them, nor is it desirable in all circumstances to have guide rails secured to the flatbed. The addition of guide rails either increases the width of the flatbed, risking violation of regulations or takes away available cargo space from the flatbed, making it less efficient.
Even when the installation of the guide rails and bows is monitored to ensure compliance with width regulations, it is still common to have the tarp attachment means (flaps, buckles, etc.) on the exterior. These means may then extend beyond the legal width permitted for the cargo bed, and the driver/operator may not even be aware of the violation. Thus, there is a need for a tarp connector system without external tarp attachment means to ensure compliance with legal restrictions on vehicle width.
The above patents are illustrative of the limitations in the known art. In addition to the above-noted limitations, the corners of the bow protrude into the interior of the cargo area, reducing the amount of available space and imposing restrictions on loading. Similarly, the tarp attachments protrude into the interior, affecting the cargo capability in the same way as the bow corners. Alternatively, they are exposed on the exterior, making them vulnerable to the elements or to theft and vandalism, and at risk of coming detached and exposing the cargo.
U.S. Pat. No. 7,344,178 to Lowry discloses a system for mounting bows to tracks carried by the trailer. The bows in Lowry are formed from a pair of headers connected to a jamb by corner brackets. The corner bracket is secured to each of the jambs and header by a tongue and socket connection with fasteners passing through the overlapping portions of the tongue and socket. In this way the bow is modular and may be shipped in a dismantled state and assembled in situ. The connection between the headers and jambs provides shoulders to enhance the rigidity of the connection and withstand the rigours of the environment in which the bows must operate.
The bracket in Lowry is formed from an extrusion such that its end faces are planar. Cover plates are secured to the end faces to enclose the bracket and tarp retainers are mounted to the exterior surface of the bracket and along the header and jambs. The number of components used in the Lowry design therefore increases the assembly time and complexity. Moreover, the tongue provided in Lowry is formed from a pair of cantilevered leaves and in practice it has been found that these may flex with the loads imposed on the bow.
U.S. patent application Ser. No. 11/754,828, the contents of which are incorporated herein by reference, discloses a tongue in which the cantilevered leaves are connected to provide an open box structure. This arrangement enhances the stiffness of the tongue. It is found however that the loads imposed on the bow are such that fore and aft swaying motion may still cause some flexure at the connection of the bracket to the headers and jambs.
It is an object of this invention to obviate or mitigate the above disadvantages.